Derating Approach for Lithium-Ion Batteries

While lithium-ion batteries are rated for specific operational and storage limits, their performance degrades over time, even when operated within these rated conditions. To meet the target lifetime requirements, designers operate and store batteries at derated capacity, voltage, current, and temperature. Although derating strategies and battery life-extension models have been reported in the literature, they do not specify what degradation data are required or how the datasheet-rated limits can be converted into quantitative derating margins. This paper presents a battery derating method that includes identifying critical datasheet-rated parameters, specifying required degradation data, defining analysis procedures, and assessing the effects on battery performance and lifetime. The method defines the minimum information required for derating analysis and introduces quantitative metrics to evaluate both the magnitude of stress reduction and the resulting degradation reduction. The developed approach is intended for product design-stage decision-making, enabling engineers to determine appropriate derating for their target application requirements and evaluate the expected degradation reduction and lifetime implications based on degradation data.